Lecture 2

Question 1

What do neurons do?

Answer 1

Send and receive messages.

Question 2

Glia Cells

Answer 2

• A supportive cell in the central nervous system.
• Unlike neurons, glial cells do not conduct electrical impulses.
• The glial cells surround neurons and provide support for and insulation between them.

Question 3

Schwann Cells

Answer 3

• A type of glia cell.

- Creates myelin sheath in the peripheral nervous system.

Question 4

Dendrite

Answer 4

Branchlike structures that extend from the cell body and specialize in receiving signals from other neurons.

Question 5

Axons

Answer 5

An axon (from Greek ἄξων áxōn, axis), also known as a nerve fibre, is a long, slender projection of a nerve cell, or neuron, that typically conducts electrical impulses away from the neuron’s cell body.

Question 6

Myelin

Answer 6

• Myelin is a fatty material that coats, protects, and insulates nerves, enabling them to quickly conduct impulses between the brain and different parts of the body.
• (It is inside the myelin sheath, protecting the nerve).

Question 7

Soma

Answer 7

The “cell body” is the bulbous end of a neuron, containing the cell nucleus.

Question 8

Astrocyte

Answer 8

• A star-shaped glia cell.
• Functions of astrocytes include physical and metabolic support for neurons, detoxification, guidance during migration, regulation of energy metabolism, electrical insulation (for unmyelinated axons), transport of blood-borne material to the neuron, and reaction to injury.

Question 9

Blood-Brain Barrier

Answer 9

• Glia creates blood-brain barriers, which is a barrier between the blood and the fluid that surrounds neurons.
• The barrier allows only some chemicals to pass, which protects the brain from potentially toxic chemicals circulating in the blood.

Question 10

Microglia

Answer 10

• A type of glia cell.

- It functions primarily as an immune cell in the CNS.

Question 11

Oligodendrocytes

Answer 11

• A type of glia cell.

- Creates myelin sheath in the central nervous system.

Question 12

Unipolar Dendrite

Answer 12

• By definition, a unipolar neuron has one axon with two branches: central and peripheral.
• These axonal branches should not be confused with dendrites.
• These sensory neurons are an exception to the typical neuron, in that they do not have separate dendrites and an axonal process, but rather one branched process that serves both functions.

Question 13

Bipolar Dendrite

Answer 13

• A type of neuron which has two extensions.
• Bipolar cells are specialized sensory neurons for the transmission of special senses.
• As such, they are part of the sensory pathways for smell, sight, taste, hearing and vestibular functions.

Question 14

Multipolar Dendrite

Answer 14

• A type of neuron that possesses a single (usually long) axon and many dendrites, allowing for the integration of a great deal of information from other neurons.
• These dendritic branches can also emerge from the nerve cell body.
• Multipolar neurons constitute the majority of neurons in the brain.

Question 15

Pyramidal Cell

Answer 15

Any of the large, triangular-shaped neurons in the cerebral cortex having one large dendrite and several smaller dendrites at the base.

Question 16

Synapse

Answer 16

• Information from one neuron flows to another neuron across a synapse.
• The synapse contains a small gap separating neurons.

Question 17

Presynaptic Neuron

Answer 17

A neuron from the axon terminal of which an electrical impulse is transmitted across a synaptic cleft to the cell body or one or more dendrites of a postsynaptic neuron by the release of a chemical neurotransmitter.

Question 18

Postsynaptic Neuron

Answer 18

A neuron to the cell body or dendrite of which an electrical impulse is transmitted across a synaptic cleft by the release of a chemical neurotransmitter from the axon terminal of a presynaptic neuron.

Question 19

The Action Potential

Answer 19

• As an action potential travels down the axon, there is a change in polarity across the membrane.
• The Na+ and K+ gated ion channels open and close as the membrane reaches the threshold potential (-40 mV), in response to a signal from another neuron.
• At the beginning of the action potential, the Na+ channels open and Na+ moves into the axon, causing depolarization (the inside of the axon becomes positive, and the outside of the axon becomes negative).
• Repolarization, (the change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential has changed the membrane potential to a positive value), occurs when the K+ channels open and K+ moves out of the axon. This creates a change in polarity between the outside of the cell and the inside.
• The impulse travels down the axon in one direction only, to the axon terminal where it signals other neurons.

Question 20

Ion Channels

Answer 20

• These are selectively permeable (allowing liquids to pass through it), water-filled molecular tunnels that pass through the cell membrane and allow ions, (such as potassium ions, sodium ions, and calcium ions), or small molecules to enter or leave the cell.
• The flow of ions creates an electrical current that produces tiny voltage changes across the neuron’s cell membrane.

Question 21

Ion

Answer 21

Electrically charged atoms.

Question 22

Ligand-Gated Ion Channels

Answer 22

A group of transmembrane ion channel proteins which open to allow ions such as Na+, K+, Ca2+, or Cl− to pass through the membrane in response to the binding of a chemical messenger (i.e. a ligand), such as a neurotransmitter.

Question 23

Voltage-Gated Ion Channels

Answer 23

• A class of ion channel’s that open and close in response to change in the electrical potential across the plasma membrane of the cell.
• These are important for conducting action potential along nerve cell processes.

Question 24

Grey Matter

Answer 24

• The part of the cortex in the brain that contains nerve cell bodies.
• It is called “gray matter,” because it is darker than the white matter.

Question 25

White Matter

Answer 25

• The part of the cortex in the brain that contains myelinated nerve fibers.
• The white matter is white because it is the color of myelin, the insulation that covers nerve fibers.

Question 26

G-Protein Coupled Receptors

Answer 26

Protein located in the cell membrane that binds extracellular substances and transmits signals from these substances to an intracellular molecule called a G protein (guanine nucleotide-binding protein).

Question 27

Agonist Receptor

Answer 27

A chemical that binds to some receptor of a cell and triggers a response by that cell.

Question 28

Antagonist Receptor

Answer 28

Prevents activation of a receptor.

Question 29

What is the resting membrane potential?

Answer 29

• The voltage maintained by a cell when it is not generating action potentials.
• The resting potential of neurons is about -65 mV.

Question 30

Nodes

Answer 30

• Nerve cells are coated with sections of myelin, and the tiny spaces between the sections are called nodes.
• As the brain sends messages through the nerves of the spinal cord, the impulses jump from node to node.
• Myelin prevents these impulses from escaping from the nerve at the wrong point.

Question 31

What is resting membrane potential?

Answer 31

• The voltage maintained by a cell when it is not generating action potentials.
• The resting potential of neurons is about -65 mV.